WO2021232313A1

WO2021232313A1 - Electrode assembly and battery

Info

Publication number: WO2021232313A1
Application number: PCT/CN2020/091385
Authority: WO
Inventors: 王攀; 陈晓; 刘慧君; 石长川
Original assignee: 宁德新能源科技有限公司
Priority date: 2020-05-20
Filing date: 2020-05-20
Publication date: 2021-11-25
Also published as: CN112689921A; JP2022537471A; JP7453968B2; US20220115712A1; EP3940857A1; KR102635825B1; KR20210063428A; EP3940857A4; CN112689921B

Abstract

Disclosed are an electrode assembly (100) and a battery (200). The electrode assembly (100) is formed by winding a first electrode plate (10), a separator film (30) and a second electrode plate (20). The first electrode plate (10) comprises a first current collector (11) and a first active substance layer (12); the first active substance layer (12) is arranged on a surface of the first current collector (11); a winding termination end (13) of the first electrode plate (10) is located on an outer side, away from a roll core, of a winding termination end of the second electrode plate (20); and the first active substance layer (12) on the winding termination end (13) of the first electrode plate (10) covers a side surface of the first current collector (11) that faces the second electrode plate (20). The electrode assembly (100) further comprises a first adhesive bonding member (41), wherein the first adhesive bonding member (41) is arranged on an outer surface of the electrode assembly (100). The above electrode assembly (100) takes the winding termination end (13) of the first electrode plate (10) as an ending end, such that the outermost ring of a battery core assembly does not have a vacuum aluminum foil design; and a gap between the electrode assembly (100) and a packing bag is eliminated by means of the first adhesive bonding member (41), thereby achieving the aim of improving the safety performance of the electrode assembly (100).

Description

Electrode assembly and battery

Technical field

This application relates to the field of batteries, and in particular to an electrode assembly and a battery with the electrode assembly.

Background technique

Generally, when winding batteries are finished, there are partially hollow aluminum foils at the end of the outer pole piece of the battery (no active material coating on both sides). The battery is generally sealed and packaged with aluminum-plastic film, and the battery is sealed with the battery. There is a gap between the shells. When this type of battery is impacted by a heavy object, because the aluminum-plastic film shell generally has good ductility, it will not break or incompletely break, but the battery itself will rupture, and the debris formed by the crushing, especially the outer ring The debris generated by the empty aluminum foil is in contact with the broken pole piece of the battery under the wrapper of the shell, resulting in short-circuit heating and even fire and explosion.

Summary of the invention

In view of the above situation, it is necessary to provide an electrode assembly with a non-voided aluminum foil on the outer layer, good safety performance, and a battery with the electrode assembly.

The embodiment of the present application provides an electrode assembly, including a first pole piece, a second pole piece, and an isolation film. The first pole piece and the second pole piece have opposite polarities, and the isolation film is disposed at all Between the first pole piece and the second pole piece, the electrode assembly is formed by winding the first pole piece, the isolation film, and the second pole piece. The first pole piece includes a first current collector and a first active material layer, the first active material layer is disposed on the surface of the first current collector, and the winding end of the first pole piece is located at the first The winding end of the second pole piece is far away from the outside of the winding core, and the first active material layer on the winding end of the first pole piece covers one of the first current collectors facing the second pole piece On the side surface, the first active material layer is not coated on the side surface of the first current collector on the winding termination end of the first pole piece away from the second pole piece. The electrode assembly further includes a first adhesive member disposed on an outer surface of the electrode assembly.

In an optional embodiment, the first adhesive member is a semi-liquid viscous material, and is disposed on the outer surface of the electrode assembly by means of spot coating, coating, or the like.

In an optional embodiment, the thickness of the first adhesive member is less than or equal to 20 um.

In an optional embodiment, the electrode assembly further includes a second adhesive member, the first adhesive member is connected to the second adhesive member, and the second adhesive member is connected to the first pole piece The winding termination end of the electrode assembly covers part of the outer surface of the electrode assembly.

Further, the thickness of the second adhesive member is 15um-25um.

In an optional embodiment, the winding end of the second pole piece extends from the winding end of the first pole piece in the winding direction.

Further, the winding termination end of the isolation film protrudes from the winding termination end of the second pole piece in the winding direction.

In an optional embodiment, the electrode assembly further includes a first tab and a second tab, the first tab is connected to the first pole piece, and the second tab is connected to the second pole piece, Along the thickness direction of the electrode assembly, the projections of the first tab and the second tab do not overlap.

Further, the winding start end of the first pole piece is provided with a first empty foil area, the winding start end of the second pole piece is provided with a second empty foil area, and the first tab is arranged on the In the first empty foil area, the second tab is arranged in the second empty foil area.

Further, the electrode assembly includes a first insulating member disposed in the first empty foil area and covering the first tab.

In an optional embodiment, the adhesive force of the first adhesive member is 100-1000 N/m, and the tensile fracture stress is less than or equal to 4000 N/m.

The embodiments of the present application also provide a battery, including an electrode assembly and a packaging body, the electrode assembly is the electrode assembly described in any one of the above, the electrode assembly is housed in the packaging body, the electrode assembly The tabs extend out of the packaging body.

The above-mentioned electrode assembly uses the first cut part as the finishing end, so that the pole piece of the outermost circle of the cell assembly does not have the design of empty aluminum foil, which saves the consumables of the aluminum foil of a single cell, and greatly reduces the possibility of aluminum debris. Eliminate the dangerous short circuit caused by debris, avoid the danger of fire and explosion of the battery, and improve the safety performance of the battery under extreme conditions of use. The surface of the electrode assembly is also provided with a first adhesive member. When the electrode assembly is installed in the packaging bag, the first adhesive member can bond the outer surface of the electrode assembly with the packaging bag. When subjected to external forces such as a drop or impact, the electrode assembly and the external packaging bag can be tightly connected without relative displacement between the two, reducing shear damage.

Description of the drawings

FIG. 1 is a schematic diagram of a winding structure of an electrode assembly in an embodiment.

FIG. 2 is a schematic diagram of a winding structure of an electrode assembly in an embodiment.

FIG. 3 is a schematic diagram of the structure of an electrode assembly in an embodiment.

Fig. 4 is a schematic diagram of the expanded structure of the first pole piece in a comparative embodiment.

Fig. 5 is a schematic diagram of the expanded structure of the first pole piece in an embodiment.

Fig. 6 is a schematic diagram of the expanded structure of the first pole piece in a comparative embodiment.

Fig. 7 is a schematic diagram of the expanded structure of the first pole piece in an embodiment.

FIG. 8 is a schematic diagram of the winding structure of the electrode assembly in a comparative embodiment.

FIG. 9 is a schematic diagram of the structure of a battery in an embodiment.

Symbol description of main components:

Electrode assembly 100

First plane 101

The second plane 102

The first arc 103

The second arc 104

Empty aluminum foil 105

Insulating tape 106

The first pole piece 10

The first episode of fluid 11

The first active material layer 12

Winding termination end 13

The first empty foil area 14

The second pole piece 20

The second episode of fluid 21

The second active material layer 22

The second empty foil area 23

Isolation film 30

Winding termination end 31

The first bonding part 41

The second bonding part 42

First pole ear 50

The second pole ear 60

First insulation piece 70

Second insulation piece 80

Battery 200

Packaging body 201

Detailed ways:

The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of this application.

It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or a central element may also be present. When an element is considered to be "connected" to another element, it can be directly connected to the other element or an intermediate element may be present at the same time. When an element is considered to be "disposed on" another element, it can be directly disposed on the other element or a centered element may exist at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of this application. The terminology used in the specification of the application herein is only for the purpose of describing specific embodiments, and is not intended to limit the application. The term "or/and" as used herein includes any and all combinations of one or more related listed items.

The above-mentioned electrode assembly uses the winding end of the first pole piece as the finishing end, so that the outermost pole piece of the cell assembly has no empty aluminum foil design, which saves the consumables of a single cell aluminum foil and greatly reduces the generation of aluminum debris. Possibly, thereby eliminating a large amount of dangerous short circuits caused by debris, avoiding the risk of fire and explosion of the battery, and improving the safety performance of the battery under extreme conditions of use. The surface of the electrode assembly is also provided with a first adhesive member. When the electrode assembly is installed in the packaging bag, the first adhesive member can bond the outer surface of the electrode assembly with the packaging bag. When subjected to external forces such as a drop or impact, the electrode assembly and the external packaging bag can be tightly connected without relative displacement between the two, reducing shear damage.

Some implementations of this application are described in detail. In the case of no conflict, the following embodiments and features in the embodiments can be combined with each other.

Please refer to FIG. 1, in an embodiment of the present application, the electrode assembly 100 includes a first pole piece 10, a second pole piece 20 and an isolation film 30. The first pole piece 10 and the second pole piece 20 have opposite polarities, the isolation film 30 is disposed between the first pole piece 10 and the second pole piece 20, and the electrode assembly 100 The first pole piece 10, the isolation film 30, and the second pole piece 20 are wound around a winding needle, and after the winding process is completed, the winding needle is taken out of the electrode assembly 100. The first pole piece 10 includes a first current collector 11 and a first active material layer 12, the first active material layer 12 is disposed on the surface of the first current collector 11, and the first pole piece 10 is wound The terminal end is located on the outer side of the winding terminal end of the second pole piece 20 away from the winding core.

In the embodiment of the present application, the first pole piece 10 is a cathode sheet, the first current collector 11 may be an aluminum foil layer, and the first active material layer 12 is a cathode active material layer, which may be LiCo. _{2, LiFeP0} ₄ other electrochemically active species can desorbing lithium ions. The second pole piece 20 is an anode piece and includes a second current collector 21 and a second active material layer 22. The second current collector may be a copper foil layer, and the second active material layer 22 may be graphite. , Soft carbon, hard carbon, Li ₄ Ti ₅ 0 ₁₂ and other electrochemically active materials that can intercalate lithium ions.

The winding end 13 of the first pole piece 10 is the structure of the outermost pole piece of the electrode assembly 100. The first active material layer 12 on the winding end 13 of the first pole piece 10 covers a side surface of the first current collector 11 facing the second pole piece 20, and the first pole piece The surface of the first current collector 11 facing away from the second pole piece 20 on the winding end 13 of 10 is not coated with the first active material layer 12.

The electrode assembly 100 further includes a first adhesive member 41 and a second adhesive member 42. The first adhesive member 41 is disposed on the outer surface of the electrode assembly 100 for bonding the electrode assembly 100 and the packaging bag. In order to reduce or eliminate the assembly gap between the two, the second adhesive member 42 is connected to the winding terminal end of the first pole piece 10 and covers a part of the outer surface of the electrode assembly 100.

In the embodiment of the present application, the first adhesive member 41 is a semi-liquid viscous material, which is arranged on the outer surface of the electrode assembly 100 by means of spot coating, coating, etc., when the battery is subjected to external forces such as a drop or impact. , The electrode assembly 100 and the external packaging bag are tightly connected, and there is no relative displacement between the two, reducing shear damage. The first adhesive member 41 can be a hot melt layer, and the material can be a rubber-based adhesive, an acrylic adhesive, etc., under certain pressure (≤3MPa) and temperature (≤120°C) conditions, it can produce viscosity , The outer surface of the electrode assembly 100 and the packaging bag are firmly bonded together. The thickness of the first adhesive member 41 is less than or equal to 20 um, the adhesive force is 100-1000 N/m, and the tensile fracture stress is less than or equal to 4000 N/m.

In an optional embodiment, the second adhesive member 42 is hot melt adhesive or insulating adhesive, and may be ultra-thin hot melt adhesive with a thickness of 15um to 25um. The material may be a rubber-based adhesive and PET Combined. Under certain pressure (≤3MPa) and temperature (≤120°C) conditions, the second adhesive member 42 can be viscous. In other words, the hot melt temperature of the second adhesive member 42 is less than or equal to 120° C., and the hot melt pressure is less than or equal to 3 MPa.

Please refer to FIG. 1 again. The outer surface of the electrode assembly 100 includes a first flat surface 101, a second flat surface 102, a first curved surface 103 and a second curved surface 104. Along the thickness direction of the electrode assembly 100 (the direction indicated by arrow A in FIG. 1), the first plane 101 and the second plane 102 are disposed opposite to each other, and along the width direction of the electrode assembly 100 (the direction indicated by arrow B in FIG. 1) Direction), the first arc surface 103 and the second arc surface 104 are disposed oppositely, and the first arc surface 103 and the second arc surface 104 are connected between the first plane 101 and the second plane 102 between.

The winding termination end of the first pole piece 10 is approximately located at the junction of the first plane 101 and the first arc surface 103, and the second adhesive member 42 is connected to the winding termination end of the first pole piece 10 It is attached to the first curved surface 103 to prevent the second adhesive member 42 from increasing the thickness of the electrode assembly 100. The first bonding member 41 is connected to the second bonding member 42 and covers the first plane 101, the second plane 102 and the second arc surface 104. In other words, the area on the outer surface of the electrode assembly 100 where the second adhesive member 42 is not attached is covered by the first adhesive member 41. In other embodiments, the winding end of the first pole piece may also be located on the first plane 101 or the second plane 102, and accordingly, the second adhesive member 42 is also attached to the first plane 101 or The second plane 102.

Further, in order to prevent the burrs generated by the lithium evolution at the end of the second pole piece 20 from piercing the isolation film 30 and connecting the first pole piece 10 to cause a short circuit, the winding end of the second pole piece 20 is rolled along the pole piece. The winding end 13 of the first pole piece 10 extends in the winding direction, and the extension length L1 is greater than or equal to 2 mm. The winding termination end 31 of the isolation film 30 extends from the winding termination end of the second pole piece 20 in the winding direction, and is attached to the inner surface of the second adhesive member 42. The isolation film The length L2 of the winding end 31 of 30 is greater than or equal to 4 mm. The winding termination end of the second pole piece 20 is covered by the winding termination end 31 of the isolation film 30 to protect and insulate the winding termination end of the second pole piece 20.

1 and 3, the electrode assembly 100 further includes a first tab 50 and a second tab 60, the first tab 50 is connected to the first tab 10, and the second tab 60 The second pole piece 20 is connected. Along the thickness direction of the electrode assembly 100, the projections of the first tab 50 and the second tab 60 do not overlap, and along the length direction of the electrode assembly 100 (the direction indicated by arrow C in FIG. 3), the The first tab 50 and the second tab 60 protrude from the same end of the electrode assembly 100. In other embodiments, the first tab 50 and the second tab 60 may protrude from different ends of the electrode assembly 100, and the application is not limited thereto.

Further, the winding start end of the first pole piece 10 is provided with a first empty foil area 14, and the winding start end of the second pole piece 20 is provided with a second empty foil area 23, and the first pole piece The ear 50 is arranged in the first empty foil area 14, and the second tab 60 is arranged in the second empty foil area 23. The electrode assembly 100 includes a first insulating member 70 disposed in the first empty foil area 14 and covering the first tab 50 to prevent burrs on the first tab 50 from piercing The isolation film 30 is in contact with the second pole piece 20 and a short circuit occurs. In an alternative embodiment, the first insulating member 70 may be an insulating tape, extending from the first tab 50 to the starting end of the first active material layer 12, and covering almost the entire first empty foil region 14, or A first insulating member 70 is additionally provided between the first tab 50 and the starting end of the first active material layer 12, so that the first empty foil region 14 can be effectively protected to avoid cracks, short circuits, and the like.

In an alternative embodiment, the second empty foil area 23 extends out of the first empty foil area 14, and the second tab 60 is arranged on the second empty foil area 23 and extends out of the first empty foil area. In the area of the empty foil area 14, even if the burrs on the second tab 60 pierce the isolation film 30, the second tab 60 is in contact with the second pole piece 20 and will not be short-circuited due to contact with the first pole piece 10. The electrode assembly 100 further includes a second insulating member 80 that covers the end of the first empty foil region 14 to prevent burrs at the end of the first empty foil region 14 from piercing the isolation film 30 and The second pole piece 20 contacts.

Please refer to FIG. 2, in one of the embodiments of the present application, the first tab 50 is disposed on the area where the first active material layer 12 is coated on the first current collector 11, and the second tab 60 The area where the second active material layer 22 is coated is arranged on the second current collector 21. Both the first tab 50 and the second tab 60 are provided with a first insulating member 70 to avoid short circuit problems. When connecting the first tab 50 and the first current collector 11, it is necessary to remove part of the first active material layer 12 first, so that part of the first current collector 11 exposes the first active material layer 12, and then the first tab 50 The first current collector 11 is welded to the exposed part. The connection mode of the second tab 60 and the second current collector 21 is similar, and will not be repeated here. In other embodiments, one of the first tab 50 and the second tab 60 may be set in the empty foil area at the core of the electrode assembly 100, and the other may be set in another position of the pole piece. This application does not Limited to this.

Please refer to FIG. 4 and FIG. 5, the position indicated by the dotted line in the figure is the cutting position of two adjacent first pole pieces 10 during the manufacturing process. When the first tab 50 is arranged in the first empty foil area 14, since the outermost circle of the electrode assembly of the comparative embodiment is provided with a section of empty aluminum foil, the length L3 of the hollow aluminum foil area of the comparative embodiment shown in FIG. 4 is obviously greater than that shown in FIG. 5. The length L4 of the hollow aluminum foil area in the embodiment of the present application, the length L4 of the hollow aluminum foil area in the embodiment of the present application only needs to meet the parameter requirements of the winding start end of the electrode assembly 100, which not only saves aluminum foil consumables, but also removes the outermost The hollow aluminum foil of the circle greatly reduces the possibility of aluminum debris in the case of extreme damage, thereby eliminating a large number of dangerous short circuits caused by the debris, avoiding the risk of fire and explosion of the electrode assembly 100, and improving the extreme use of the electrode assembly 100 Safety performance.

6 and 7, when the first tab 50 is provided in the area where the first current collector 11 is coated with the first active material layer 12, since the outermost ring of the electrode assembly of the comparative embodiment is provided with a section of empty aluminum foil, the figure In the comparative example shown in Fig. 6, there is a section of single-sided area and a section of empty aluminum foil between two adjacent first pole pieces 10, and the single-sided area is the winding end 13 of the first pole piece 10. In the embodiment of the present application, the empty aluminum foil between two adjacent first pole pieces 10 is eliminated, and there is only a single-sided area (the winding end 13 of the first pole piece 10), so that the first current collector 11 The first active material layer 12 on the surface can be continuous, which simplifies the manufacturing process of the first pole piece 10 and helps to improve production efficiency.

Referring to FIG. 8, in a comparative embodiment, a part of the hollow aluminum foil 105 exists at the outer tail of the electrode assembly (no active material coating on both sides), and a layer of insulating tape 106 is attached to the tail hollow aluminum foil and the coating edge of the tail. The hollow aluminum foil 105 and the insulating tape 106 are both located on the first plane 101 or the second plane 102 of the electrode assembly.

The specific content of the impact test of the electrode assembly 100 of the comparative example and the embodiment of the present application is: placing the fully charged electrode assembly on a flat iron plate, and placing a round rod with a diameter of φ15.8±0.1mm and a length of at least 6cm perpendicular to the test For the sample (position of the tab), use a weight of 9.1±0.1Kg at a distance of 61±2.5cm from the intersection of the round bar and the sample, and fall in a vertical free state to compare the pass rate of the electrode assembly. The passing criterion is that after the test is completed, the electrode assembly does not catch fire or explode.

The impact test data of the electrode assembly 100 of the comparative example and the example of the present application is shown in the following table.

类别category	撞击通过数Number of passes	通过比例Pass ratio
实施例Example	9/10pass9/10pass	90％90%
对比例Comparison	0/10pass0/10pass	0％0%

The specific content of the drop test of the electrode assembly 100 of the comparative example and the embodiment of the present application is: the electrode assembly is half-charged, put into a special fixture, properly fixed, and then the fixture is placed at a distance of 1m for a drop test. One round at a time, a total of four rounds were dropped to compare the pass rate of the cell; the criterion is that after the test is completed, the top seal is flushed, the liquid leaks, the 24h pressure drop is >30mV, and the aluminum foil is torn.

The thickness of the electrode assembly in the first set of tests is 3mm (11 layers rolled), and the test results are shown in the table below.

The thickness of the electrode assembly in the second set of tests is 5mm (wound 19 layers), and the test results are shown in the table below.

In combination with the data in FIGS. 4 to 8 and the above-mentioned surface, the embodiment of the present application is compared with the comparative example, the outermost ring of the electrode assembly 100 is designed with no hollow aluminum foil, which reduces the possibility of aluminum debris, thereby eliminating debris caused by To avoid the danger of fire and explosion of the electrode assembly 100, improve the safety performance of the electrode assembly 100 under extreme use conditions. At the same time, the first adhesive 41 provided on the outer surface of the electrode assembly 100 makes the electrode assembly 100 and the external packaging bag Can be tightly connected together, there is no relative displacement between the two, reducing shear damage.

Referring to FIG. 9, an embodiment of the present application further provides a battery 200, including a packaging body 201 and the electrode assembly 100 in the embodiment. The electrode assembly 100 is housed in the packaging body 201, and the electrode assembly The tabs of 100 extend out of the packaging body 201.

The above embodiments are only used to illustrate the technical solutions of the application and not to limit them. Although the application has been described in detail with reference to the above preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the application can be modified or equivalently replaced None should deviate from the spirit and scope of the technical solution of this application.

Claims

An electrode assembly, including:

First pole piece

A second pole piece, the polarity of which is opposite to that of the first pole piece; and

An isolation film, the isolation film is arranged between the first pole piece and the second pole piece, and the electrode assembly is wound by the first pole piece, the isolation film and the second pole piece form;

It is characterized in that the first pole piece includes a first current collector and a first active material layer, the first active material layer is disposed on the surface of the first current collector, and the winding termination end of the first pole piece The winding end of the second pole piece is located outside the winding core, and the first active material layer on the winding end of the first pole piece covers the first current collector toward the second One side surface of the pole piece, and the first active material layer is not coated on the side surface of the first current collector on the winding termination end of the first pole piece facing away from the second pole piece;

The electrode assembly further includes a first adhesive member disposed on an outer surface of the electrode assembly.
8. The electrode assembly of claim 1, wherein the first adhesive member is a semi-liquid viscous material and is disposed on the outer surface of the electrode assembly by means of spot coating, coating, or the like.
The electrode assembly of claim 1, wherein the thickness of the first adhesive member is less than or equal to 20um.
The electrode assembly of claim 1, wherein the electrode assembly further comprises a second adhesive member, the first adhesive member is connected to the second adhesive member, and the second adhesive member is connected to The winding termination end of the first pole piece covers a part of the outer surface of the electrode assembly.
5. The electrode assembly of claim 4, wherein the thickness of the second adhesive member is 15 um to 25 um.
The electrode assembly of claim 1, wherein the winding end of the second pole piece extends from the winding end of the first pole piece in the winding direction.
8. The electrode assembly of claim 6, wherein the winding end of the separator film extends from the winding end of the second pole piece in the winding direction.
The electrode assembly of claim 1, wherein the electrode assembly further comprises a first tab and a second tab, the first tab is connected to the first tab, and the second tab The second pole piece is connected, and along the thickness direction of the electrode assembly, the projections of the first pole and the second pole do not overlap.
8. The electrode assembly according to claim 8, wherein the winding start end of the first pole piece is provided with a first empty foil area, and the winding start end of the second pole piece is provided with a second empty foil. Zone, the first tab is arranged in the first empty foil zone, and the second tab is arranged in the second empty foil zone.
9. The electrode assembly of claim 9, wherein the electrode assembly comprises a first insulating member, and the first insulating member is disposed in the first empty foil area and covers the first tab.
8. The electrode assembly of claim 1, wherein the adhesion force of the first adhesive member is 100-1000 N/m, and the tensile fracture stress is less than or equal to 4000 N/m.
A battery comprising an electrode assembly and a packaging body, wherein the electrode assembly is the electrode assembly according to any one of claims 1-11, the electrode assembly is contained in the packaging body, and the electrode assembly The tabs extend out of the packaging body.